The present invention relates generally to pipe fittings or repair assemblies for repairing ruptured or leaking pipes.
Various types of pipe fittings are known which may be used for repairing ruptured pipes or for coupling together the ends of adjacent pipe sections. Gas, oil or other pipelines on land or under the sea often become damaged or ruptured as a result of ground movement, vandalism, improper insertion or general pipe wear. Repairs of these types of pipeline typically involve cutting out the defective section of pipe and replacing it with a new section, either by welding the new section in place or by bolting suitable couplings over the adjacent pipe, and back welding on the repair device itself. This is relatively time consuming.
In some areas welding of pipeline joints is a problem due to explosion risk. For example, oil refineries and the engine rooms of ships are areas of extreme explosion or fire hazard, and if repairs requiring on-site welding must be made to pipes in these areas, the areas to be worked must first be freed of all flammable gases and liquids, a process known as "gas freeing". This is a costly and lengthy process.
Thus coupling assemblies involving bands and clamps have been proposed in the past for pipe repairs to avoid the need for on-site welding. These assemblies typically lack the reliability and durability of a welded joint, and most require the damaged section, of pipe to be cut out and replaced with a new section, which is relatively time consuming and expensive. In U.S. Pat. No. 4,662,660 of Perea, for example, a weldless pipe fitting is described which has two sealing sleeves for fitting over respective adjacent pipe ends, the sealing sleeves having a frusto-conical outer surfaces, and an outer collar having corresponding frusto-conical inner surfaces which mate with the respective sleeves to urge them into sealing engagement with the pipes. A locking assembly is applied to the opposite ends of the collar to urge the sleeves into the collar and into sealing engagement with the pipes. Some repair assemblies are known which allow a fracture to be repaired without cutting out the damaged section. These generally comprise split sleeves which must be bolted together, and are not normally suitable for high pressure applications.